With the advent of computers, and in particular personal computers, a number of programs have been developed that map celestial objects from their normal spherical coordinates into two-dimensional coordinates using well-known map projection techniques commonly used by cartographers. Celestial objects such as stars, nebulae, and planets have their positions in the sky recorded in a spherical coordinate system similar in concept to use of latitude and longitude to record the positions of geographic locations on the earth.
In the terrestial coordinate system, the lines of longitude pass through the earth's North and South poles, while the parallel lines of latitude intersect these lines of longitude to form a spherical grid. The lines of longitude start at zero degrees and extend to 180 degrees east of the prime meridian (which passes through Greenwich, England) to encompass one hemisphere, and extend another 180 degrees west of the prime meridian to encompass the earth's other hemisphere. Thus the lines of longitude extend throughout 360 degrees of a sphere.
Similarly, in celestial coordinates there are lines that pass through the North and South poles of the celestial sphere. These lines are known as right ascension. Instead of these lines being in units of degrees, they are in units of hours, where one hour of right ascension is equal to 15 degrees. Thus to define all 360 degrees of the celestial sphere, there are 24 hours of right ascension, ranging from zero hour to twenty-three hours.
The parallels of latitude on the terrestial sphere are in units of degrees, ranging from zero degrees on the equator to 90 degrees at the North and South poles. There are thus 90 degrees of latitude north of the equator and 90 degrees of latitude south of the equator.
The corresponding lines that define the celestial sphere are call lines of declination. Like the terrestial lines of latitude, these lines of declination are in units of degrees both north and south of the celestial equator. The lines north of the celestial equator are called positive or plus (+) lines of declination while the lines south of the celestial equator are called negative or minus (-) lines of declination.
An excellent discussion of the celestial sphere and its coordinate system is presented in Guy Ottewell's The Astronomical Companion, pages 4-11 (published by G. Ottewell at the Department of Physics, Furman University, Greenville, S.C.
As is well known for terrestial mapping, there are many mathematical projection techniques to translate points on a spherical surface into points on a planar surface. An in depth review of virtually all the well-known mapping techniques is presented in Map Projections--A Working Manual, by John P. Snyder (published by the U.S. Geological Survey, Professional Paper 1395, dated 1987). One such technique which has also found use for projecting the celestial sphere onto a planar surface is known as a stereographic projection. According to Snyder, this map projection technique has probably been known since the times of the ancient Egyptians. The technique projects all points on a hemisphere to a plane perpendicular an axis through the sphere, with the lines of projection emanating from the axis' pole opposite the plane (see Map Projections, above, at pages 154-163, as well as FIG. 1 herein).
Richard Berry wrote a computer program in the BASIC language called Stars. Bas (as published in the August, 1985 issue of Astronomy magazine, pages 66-71) which performs a stereographic map projection of celestial objects onto the planar surface of a computer monitor. The stereographic map projection technique used by Berry is used in the preferred embodiment of the present invention, although other types of map projection techniques can also be used.
The stereographic map projection technique is used in the present invention to achieve a new result; namely, to generate two corresponding but different planar projections of the same portion of the celestial sphere. One projection is for viewing by the observer's left eye while the other projection is for viewing by the observer's right eye. The difference between the two projections is a function of the celestial object's distance from the earth, so that celestial objects closer to the earth than other celestial objects are presented with a greater horizontal offset. In this way, when the two images are merged into one by the observer's eyes (and brain) the celestial objects will be perceived in three dimensions with respect to each other.
Due to the extreme distances of celestial objects from the earth, the horizontal offsets displayed actually represent views of the celestial objects as if the viewer's left and right eyes were separated from one another by up to trillions of miles, and thus the present invention is able to present a view of the heavens heretofore unobservable.